Transitions between transmission lines and other modules are employed in diverse systems. A common connection is, for example, a waveguide-to-microstrip transition. Usually, the requirements on the precision of the connection are high, since even small deviations will degrade the performance resulting in a considerable insertion loss. Especially waveguide-to-microstrip transitions are extremely sensitive to geometry errors. Simulations show that a length difference of only 50 microns in a microstrip can result in an insertion loss increase of 0.5 dB to 1.2 dB.
In practice, transmission lines and other modules are connected mechanically to provide the needed transition. To this end, screwing, soldering or similar methods are employed. Such methods lead, however, to rather inaccurate results and the tolerances can be quite large so that the requirements cannot be met satisfactorily. To connect transmission lines to other modules mechanically also constitutes an extremely difficult and time-consuming assembly phase. In addition, special tools, like registration devices and Computer Aided Enginering (CAE) tools, are required.